Overhead-suspended systems are known in the art and currently in operation. Typically, car bodies are suspended directly from and below trucks. In one case the trucks have steel wheels running on top of a single steel rail, being truly a “Monorail”. This allows the car bodies to swing out in curves but imposes limits on speed because of the suspension system. In another case, the trucks run inside a duct on rubber tires with side wheels to guide the non-steering rubber wheels with the car bodies suspended directly from the trucks. The roof of each car body typically serves as a rigid frame to which the trucks are attached. This fixes the distance between the trucks. The propulsion and braking forces generated in the trucks are limited as a result of the force being transmitted directly down to the car bodies through their suspension attachments.
In such cases the direct suspension of the bodies from the trucks results in difficulties when detaching or exchanging the car bodies. It also imposes limitations on the ability to couple vehicles into trains because such coupling is done at the car bodies and not at the trucks where the traction forces are generated.
As will be described for embodiments of the present invention, an Overhead-Suspended Light Rail (OSLR) system overcomes known limitations in typical overhead transport systems. The disadvantages that embodiments of the OSLR of the present invention can overcome include, but are not limited to the following herein presented, by way of example:
Light Rail Transit (LRT) uses tracks at grade level occupying land that is typically sterilized against other uses. In many places, the work of installing these tracks requires purchase of property, displacement of occupants, and disruption of commercial operations. In streets, it disrupts traffic movements for long periods of time. Especially costly is the needed utilities relocation. Cities that did not plan for a transit trench now require that whole drainage systems, natural gas, water service, telephone, cable TV and power be relocated. In mature cities the location of these is not accurately defined, thus creating expensive and hazardous conditions for workers. Embodiments of the OSLR of the present invention incorporates LRT technology but places tracks and train operations overhead, allowing existing land uses to continue without conflict and minimizes traffic interruption during construction. This avoids a need for new laboratory research, requiring that the system be engineered and installed only in an appropriate location.
LRT tracks and switches at grade are sensitive to climatic conditions such as snow, freezing rain and flooding from heavy rainstorms. The OSLR places the tracks, signals and power contact strips inside a covered duct with full protection from the weather.
LRT vehicles operating in the streets absorb traffic capacity from roadways already congested with other traffic. The vehicles become equally delayed because they cannot move any faster than this same congestion. They introduce risks of collisions, injuries and deaths with vehicles and pedestrians, and impose limits of permissible operating speeds. These risks of moving trains in the streets require that such vehicles be manually operated, preventing any prospect of full automation, with its associated economic and safe operation. There are strict limits on the lengths and speeds of trains in the streets, and on the frequency of trains, making it difficult to expand capacity to meet future growth. The OSLR herein described operates trains safely overhead and well separated from other operations and land uses on the ground, thus allowing full automation with train lengths and operating speeds free from speed restrictions typically placed at ground level.
Passengers and freight riding in LRT vehicles mounted above their wheels (bottom-supported) typically feel the shocks and lateral accelerations generated below them. Typical vehicle designs attempt to minimize this effect, but do not eliminate it. Passengers and freight in embodiments of the OSLR vehicles of the present invention ride below the wheels. Suspending the car body beneath a carrying vehicle effectively suspends the body like a pendulum, isolating it from lateral impacts sustained by the carrying vehicle and therefore affording a much smoother ride for passengers and freight.
Bottom-supported vehicles impose strict limitations on an amount of super-elevation to be tolerated on curves, directly impacting permissible speeds of vehicles traversing curves. The OSLR vehicles of the present invention avoid known constraints. As a result, greater super-elevation may be placed on curves, and the swing out of the car bodies enhances the effect to double the effective super-elevation allowing significantly faster operating speeds on the curves.
Further, there is a need for shorter journey times, for reducing the size of vehicle fleet required to fill any given operating schedule, for improving the productivity of the train equipment, and for marketing a quality of service superior to alternative systems and more attractive to the public.